Central heating system for heating rooms

ABSTRACT

The invention pertains to a central heating system ( 10 ) for heating rooms of one or more buildings ( 2 ) with a pipeline network with supply and return lines ( 18, 20 ), at least one flow limiter ( 26 ) arranged in the pipeline network, a fluid as thermal medium in the pipeline network, several heating circuits ( 32 ) each connected to the pipeline network via circuit supply and return lines ( 24, 30 ), each circuit having a temperature control valve ( 28 ) for regulation/control of room temperature and at least one heating element ( 22 ). The invention is characterized in that a flow limiter ( 26 ) is inserted into each circuit supply or return line ( 24, 30 ), associated with each heating circuit ( 32 ).

TECHNICAL FIELD

[0001] The invention pertains to a central heating system for heating rooms in one or more buildings with a piping network with supply and return lines, and more particularly to a system having several subcircuits, such as for heating rooms on different floors of a building.

BACKGROUND

[0002] Known central heating systems generally have a heat source and a pipeline system for transporting a thermal medium to heat individual rooms. As a rule, water is used as the thermal medium.

[0003] Depending on the complexity of the heating system, the pipeline system is composed of several subcircuits which extend, for instance, in individual floors of a multistory building. The subcircuits are supplied by vertical lines.

[0004] As a rule, a subcircuit of the pipeline system consists of separate supply and return lines, at least one line barrier (i.e. check valve and/or back flow preventor) and several heating circuits parallel to one another connected to the supply and return lines. A heating circuit can have only one heating element or several heating elements arranged in series and connected via supply and return lines to the supply and return lines of the subcircuit.

[0005] In the subcircuit supply line, a line barrier is arranged at the start of each subcircuit. The line barrier ensures a uniform distribution of water in the subcircuits. It is intended thereby to minimize irregular flow through the heating circuits and thus the heating elements because of, for instance, the long distance from the main vertical supply line or to frictional losses due to pipe curvatures.

[0006] The regulation or control of desired room temperature is accomplished by way of valves, specifically, temperature control valves, inserted into the heating circuits. The valve aperture and thus the volume flow of thermal medium flowing into the heating circuits or heating elements is regulated by a pressure-sensitive actuator. A spring acts in the closing direction on the actuator.

[0007] Known central heating systems have the disadvantage that the installed circuit barriers produce pressure gradients of varying magnitudes independently of the flow amount. Consequently, the hysteresis of the valves increases or is displaced, and therefore, the individual temperature settings of the individual rooms cannot be guaranteed.

[0008] If the central heating system is operating in the full load range, then there is a high flow velocity of the thermal medium in the pipeline system. Associated with this high flow velocity, however, is a high pressure gradient at the circuit barriers. This has the consequence that a smaller differential pressure is present at the temperature control valves for controlling the flow of the thermal medium and thus a larger differential force consisting of differential pressure and spring force acts in the closing direction on the actuator. The actuator is consequently pressed in the closing direction, so that the volume flow of thermal medium decreases. The premature valve closure induced thereby has the result that the room temperature set/desired at the valves is not reached. In order to reach the desired room temperature nonetheless, manual readjustment of the valves is required, which is linked to increased energy consumption and increasing costs.

[0009] A similar phenomenon occurs in the partial load range of the central heating unit. Because of the then prevailing low flow velocity of the thermal medium, only a small pressure gradient can be observed at the circuit barriers. This has the consequence that a higher pressure is present at the temperature control valves located in the heating circuits and therefore a lower differential pressure acts in the closing direction on the actuator. The actuator is thereby pressed less in the closing direction. Because of the elevated pressure, the temperature control valves close with a temporal offset, that is to say, at higher room temperatures. This is once again associated with elevated energy consumption and rising costs.

SUMMARY OF THE INVENTION

[0010] The invention is based on the problem of refining a central heating unit for heating rooms according to the type specified above such that energy savings are achieved by avoiding the aforementioned disadvantages with a simple design.

[0011] This problem is solved by the present invention which is based on the insight that, by setting a nearly constant pressure level in the pipeline system of the heating system, particularly at the temperature control valves, large energy savings and a reduction of operating costs are possible.

[0012] According to the invention, therefore, each heating circuit is assigned a flow limiter, which provides nearly constant pressure in the local heating circuit as it is inserted in the circuit supply or circuit return line, independently of the number of heating elements in the heating circuit. A constant pressure level at the valves can thereby be guaranteed in a simple manner.

[0013] In order to ease the design of larger heating systems consisting of vertical lines and several subcircuits, the installation of flow limiters is now done exclusively in the supply and return lines of each heating circuit. The circuit barriers previously utilized are now unnecessary.

[0014] It is of no consequence whether a heating circuit contains only one heating element or several heating elements connected in series. The flow limiter in the heating circuit may be installed in the supply flow line, optionally upstream or downstream of the temperature control valve, or in the return flow line.

[0015] Depending on the embodiment of the invention, the flow limiter and the valve may be designed as an integral structural unit.

[0016] The flow limiters are designed so that an equally large pressure gradient is achieved at all flow limiters, independently of the existing pressure conditions and, in particular, independently of the size, number and construction of the heating element in a heating circuit.

[0017] The installation site of the flow limiters in the individual heating circuits may be consistent or different for all subcircuits of a heating system.

[0018] So that good maintenance of the system can be assured, it is preferred that the flow limiters are interchangeable throughout the pipeline network.

[0019] According to one embodiment of the invention, the flow limiters are laid out such that an equally large pressure gradient is achieved at all flow limiters, independent of the existing pressure conditions and, in particular, independent of the size, number and construction of the heating elements of a heating circuit. This is important when heating elements of different size, which are supplied differing amounts of thermal medium per unit time, are employed. The flow limiter is thus designed in regard to its size as a function of the size of the heating element and as a function of the pressure in the pipeline network.

[0020] Additional characteristics and advantages may be deduced from the description below of an embodiment of the invention in conjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 is a schematic circuit diagram of a central heating system according to the invention in a building consisting of several floors.

DETAILED DESCRIPTION OF THE INVENTION

[0022]FIG. 1 schematically shows a building 2 that has a service room 4 in a basement for accommodating a central heat source 6 and three heated stories 8 a-8 c, namely ground floor 8 a, first upper floor 8 b and second upper floor 8 c. Three subcircuits 12 a, 12 b and 12 c, which are part of a central heating system 10 according to the invention, are installed in the building 2. Subcircuit 12 a extends in a ground floor 8 a, subcircuit 12 b in a first upper floor 8 b, and subcircuit 12 c in a second upper floor 8 c.

[0023] Subcircuits 12 a-12 c each have a subcircuit supply flow line 18 and a subcircuit return flow line 20 which run separately. Subcircuits 12 a-12 c are connected to the central heat source 6 via vertical supply line 14 and vertical return line 16, each subcircuit also having a subcircuit supply line and a subcircuit return flow line.

[0024] In each heated story, 8 a-8 c, three heating circuits, a first heating circuit 32, a second heating circuit 34 and a third heating circuit 36, are connected to the corresponding subcircuit 12 a, 12 b and 12 c. Every heating circuit 32, 34 and 36, is connected via a supply line 24 to a subcircuit supply line 18 of the associated subcircuit 12 a-12 c and via a return flow line 30 to a subcircuit return flow line 20 of the associated subcircuit 12 a-12 c. While the first two heating circuits 32 and 34 each have one heating element 22, two heating elements 22 are arranged in series in the third illustrated heating circuit 36. The diameters of supply flow line 18 and return flow line 20 of each subcircuit 12 a-12 c are identical.

[0025] A temperature control valve 28 for regulating the room temperature is inserted in each supply line 24 of each heating circuit 32, 34 and 36.

[0026] A flow limiter 26 is installed in the supply line 24 or the return line 30 of each heating circuit 32. The installation site of the flow limiter 26 in the supply line 24 or the return line 30 of each heating circuit 32, 34 and 36 is identical inside a given subcircuit 12 a, 12 b or 12 c, but for illustrative purposes, the installation site differs for each individual one of the three subcircuits 12 a, 12 b and 12 c. In the subcircuit 12 a, the flow limiter 26 is downstream of the temperature valve 28 in the supply line 24 of each heating circuit 32, 34 and 36, and in the subcircuit 12 b, the flow limiter 26 is upstream of the temperature control valve 28 in the supply flow line 24 of each heating circuit 32, 34 and 36. In the subcircuit 12 c, the flow limiter 26 is inserted in the return line 30 of each heating circuit 32, 34 and 36 and thus downstream of the temperature control valve 28 and the heating element 22 for heating circuit 32 and 34, or both heating elements 22, for heating circuit 36.

[0027] In the temperature control valves 28 that are opened in the majority of cases, for instance, differentially high flow velocities of the thermal medium occur in the central heating system 10. By providing flow limiters 26 in supply flow lines 24 or return flow lines 30 of each heating circuit 32, 34 and 36, an essentially constant flow velocity in the central heating system 10 results. Because of the essentially constant flow velocities, pressure fluctuations inside the pipeline system of the central heating system 10 are avoided, in particular, in the supply flow lines 24 and the return flow lines 30 of each heating circuit 32, 34 and 36, and thus at the temperature control valves 28. Consequently the hysteresis of the temperature control valves 28 with respect to one another remains unchanged. This has the advantage that the room temperature is more precisely regulated and thus manual resetting of the room temperature is no longer necessary; consequently energy savings are achieved.

[0028] The invention is characterized in that considerable energy can be saved by the installation of flow limiters in individual heating circuit supply flow lines 24, optionally upstream or downstream of the temperature control valve 28, or in the individual heating circuit return flow line 30 of each heating circuit 32, 34 and 36. 

I claim:
 1. A central heating system (10) for heating rooms in one or more buildings (2) with a pipeline network having supply and return pipelines (18, 20), at least one flow limiter (26) arranged in the pipeline network, a fluid thermal medium located in the pipeline network, a plurality of heating circuits (32) each connected to the pipeline network in parallel to each other via circuit supply and return lines (24, 30), each circuit having a valve (28) for regulation/control of room temperature and at least one heating element (22), characterized in that a flow limiter (26) is inserted into the circuit supply or return line (24, 30), and is associated with each heating circuit (32).
 2. The central heating system according to claim 1, characterized in that the pipeline network consists of a plurality of subcircuits (12 a, 12 b, 12 c), arranged on different floors (8 a, 8 b, 8 c) of a building (2), to which a plurality of subcircuit heating circuits (32) are connected in parallel to each other.
 3. The central heating system according to claim 2, characterized in that the plurality of subcircuits (12 a, 12 b, 12 c) are supplied via vertical supply and vertical return lines (14, 16).
 4. The central heating system according to claim 1, characterized in that the flow limiters (26) are inserted exclusively into the circuit supply or return lines (24, 30) of each heating circuit (32).
 5. The central heating system according to claim 1, characterized in that the flow limiter (26) is installed in a supply line (24) of a heating circuit (32).
 6. The central heating system according to claim 5, characterized in that the flow limiter (26) is located upstream of the valve (28).
 7. The central heating system according to claim 5, characterized in that the flow limiter (26) is located downstream of the valve (28).
 8. The central heating system according to claim 1, characterized in that the flow limiter (26) is installed in the circuit return line (30) of a heating circuit (32).
 9. The central heating system according to claim 2, characterized in that an installation site of each flow limiter (26) in the circuit supply or return lines (24, 30) of the heating circuits (32) is uniform for all heating circuits (32) of a subcircuit (12 a, 12 b, 12 c).
 10. The central heating system according to claim 9, characterized in that the installation site of each flow limiter (26) in the circuit supply or return line (24, 30) of the heating circuits (32) is different in at least two subcircuits (12 a, 12 b, 12 c).
 11. The central heating system according to one of claim 1, characterized in that an installation site of the flow limiters (26) in the circuit supply or return outflow line (24, 30) of the heating circuits (32) is uniform for all heating circuits (32) in the pipeline network.
 12. The central heating system according to claim 1, characterized in that the flow limiters (26) are interchangeable in the pipeline network.
 13. The central heating system according to claim 1, characterized in that the valve (28) and the flow limiter (26) form an integral structural unit.
 14. The central heating system according to claim 1, characterized in that the flow limiters (26) provide an equally large pressure gradient at all flow limiters (26), independent of the existing pressure condition and independent of the size, number and construction of the heating elements (22) of a heating circuit (32). 